This invention relates generally to a borescope or endoscope for providing full color video images of inaccessible objects of the type having a cable actuated steering section, and more particularly to a compact portable battery operated borescope having a servo motor controlled steering section.
A borescope is generally characterized as an elongated flexible insertion tube with a viewing head at its distal end and a control and processing section at its proximal end. The control section has generally included one or two pairs of control cables extending from the bendable tube section through the remainder of the insertion tube to connect with the steering control mechanism in the control section. These steering mechanisms typically have involved a rack and pinion steering mechanism with large control knobs for manipulation of the steering in two planes disposed ninety degrees to each other. One or both pairs of these cables are differentially displaced for bending the steering section to facilitate the inspection of an object. Various devices have been provided in the prior art for realizing a full color video picture of a target situated within a remote cavity. These devices have been gradually improved over time to where today, most devices of this type employ an external light source conveyed to the image viewing head by fiber optic bundles, together with a solid state image sensor and lens system positioned in the distal end of the insertion tube of the borescope connected to an external video processing system and standard television format display equipment.
Endoscope/borescope systems of this general type have been disclosed in various patents owned by a common assignee of the present applicant, such as Moore et al. U.S. Pat. No. 4,253,447; Moore et al. U.S. Pat. No. 4,261,344; and Danna et al. U.S. Pat. No. 4,491,865. Another endoscope system is shown in Omagari U.S. Pat. No. 4,621,618, which describes a central control/display/light station, and a drive motor body for the insertable endoscope portion. The central control has a joystick actuated motor drive circuit for a motor mounted adjacent to and which manipulates the wire controlled bendable section of the insertion tube. This rather large cumbersome system requires a paramedic to handle the endoscope while the doctor operates the device from the control station. Also, the apparatus obviously is not portable.
As part of the need for greater flexibility and portability, the control of the steering function of a borescope has had to be simplified and improved both from an operating and from an adjustability and maintenance viewpoint. Not only is it important to be able to operate a compact portable system by a single person from a variety of locations relative to the main processing module, but the requirement for the precise positioning and for very tortuous access in industrial products has greatly increased the demand for maintaining the instruments in optimum steering adjustment at all times.
As is well known in the art, frequent use or abuse of a cable actuated bending section of a borescope will stretch the cables to the point that steering accuracy is lost and precise positioning is impossible. One of the major problems faced by the industry is the constant need to readjust and refurbish the steerable insertion tube portions of borescope apparatus. A great deal of time and money is invested constantly by users of these systems to repair and readjust bendable insertion tubes in which the cables have been stretched or broken.